US20150029516A1

US20150029516A1 - Device for optically scanning and measuring an environment

Info

Publication number: US20150029516A1
Application number: US14/374,054
Authority: US
Inventors: Christoph Neundorf; Reinhard Becker
Original assignee: Faro Technologies Inc
Current assignee: Faro Technologies Inc
Priority date: 2012-01-25
Filing date: 2012-12-12
Publication date: 2015-01-29
Also published as: DE102012100609A1; US9417056B2; GB2512515A; GB2512515B; GB201410276D0; CN103857984A; WO2013110402A1; CN103857984B; JP2015510114A; JP6027141B2

Abstract

A laser scanner device for optically scanning and measuring an environment includes a base, a measuring head which is rotatable relative to the base, and a mirror which is rotatably relative to the measuring head, wherein, in at least one operating mode, the laser scanner is mounted on a cart by a mounting device, the cart moves the base which is fixedly connected with the mounting device, the measuring head rests relative to the base, the mirror rotates, and the measuring head is locked with the mounting device by a locking mechanism.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present patent application is a National Stage Patent Application of, and which claims priority to, PCT Patent Application No. PCT/EP2012/075178, filed on Dec. 12, 2012, which claims the benefit of U.S. Provisional Patent Application No. 61/592,024, filed on Jan. 30, 2012, and of German Patent Application No. 10 2012 100 609.1, filed on Jan. 25, 2012, and all of which are hereby incorporated by reference herein.

BACKGROUND OF THE INVENTION

The invention relates to a device for optically scanning and measuring an environment.
By a laser scanner device, such as is known for example from German Patent Application No. DE 20 2006 005 643, the environment of the laser scanner can be optically scanned and measured.

SUMMARY OF THE INVENTION

Embodiments of the present invention are based on the object of improving a device of the type mentioned hereinabove.
Different operating modes can be provided for the laser scanner. In at least one operating mode (e.g., a helix mode), the laser scanner as a whole is moved by a cart on which the base of the laser scanner is mounted by a mounting device. The measuring head of the laser scanner rests relative to the base, while the mirror of the laser scanner rotates about its horizontal axis relative to the measuring head. The term “cart” may include any vehicle suitable for transporting the operating laser scanner.
According to embodiments of the present invention, in addition to a fixed connection between the base and the mounting device, the measuring head is locked together with the mounting device through use of corresponding first and second locking mechanisms. A pivot bearing between the measuring head and the base is thus bridged and relieved. In particular, static strains caused by a non-uniform clamping of the measuring head when the base is mounted on the mounting device and dynamic loads caused by moments of inertia of the measuring head are avoided.
A mechanical connection of the base with the mounting device and/or the locking of the measuring head with the mounting device may take place without backlash, for example by providing conical elements or elements which taper in a wedge-shaped manner. An electrical connection between the base and the mounting device may be optional and can be replaced, for example, by a direct connection (e.g., a cable) between the laser scanner, (for example, the base of the laser scanner) and the cart.
In another operating mode (e.g., a sphere mode) of the laser scanner, the base is stationary, and the mirror and the measuring head rotate about their axes.
A “horizontal” arrangement of the axis of rotation of the mirror and the “vertical” arrangement of the axis of rotation of the measuring head refer to an ideal alignment of the laser scanner. In case of an alignment of the laser scanner which is inclined with respect to the ideal alignment, the terms “horizontal” and “vertical” are interpreted in a relatively broader sense.
The components of the laser scanner may be arranged in two parts of the measuring head and in a traverse of the carrying structure which connects the two parts together. The carrying structure may form a part of the housing of the laser scanner, for example a bottom part and/or a central part between the two parts of the measuring head. To reduce the weight of the laser scanner, a shell may be provided as part of the housing, for example one shell each for each of the two parts of the measuring head, the shells comprising a relatively light material, for example plastic, and covering the corresponding components of the laser scanner for protection. To protect the shell, a yoke may be provided, for example one yoke for each shell, the yoke partially covering the outside of the shell and comprising a relatively light material as well, for example aluminum. The yokes can be omitted in alternative embodiments, for example if the shells are configured in a more stable manner and connected with the carrying structure.
The carrying structure which, for reasons of weight, may comprise aluminum as well, and may be provided with walls which fix the components with the optics and with the rotating mirror. The walls can also close the semi-open shells. The yoke may extend along the outer edges and/or obliquely over the outer surfaces of the shell and is fixed to the carrying structure, for example at the ends thereof, and if required also in the center thereof, at one of the two walls. In addition to the protective function, further functions can be integrated in the yokes.
The first locking mechanism, for example fixed notches, may be configured on the yokes. Also, a second locking mechanism may be provided, for example movable pawls, locks or similar, which are supported on the mounting device. The movable second locking mechanism then engages in the fixed first locking mechanism. The assignment of the fixed and of the movable locking mechanisms to the measuring head and to the mounting device, respectively, may also be reversed.
The mechanical connection of the base with the mounting device and the first locking mechanism between the measuring head and the mounting device may be arranged crosswise, to obtain a relatively stable support of the laser scanner on the mounting device. The terminal for the electrical connection with the cart may be located adjacent to the first locking mechanism and thus outside the space angle which can be reached by the emission light beam.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below on the basis of an exemplary embodiment illustrated in the drawing, in which

FIG. 1 is a schematic illustration of the laser scanner during operation, with a sketched cart;

FIG. 2 is a perspective illustration of the laser scanner;

FIG. 3 is a perspective illustration of the mounting device, and

FIG. 4 is an underside view of the laser scanner.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-4, a laser scanner 10 is provided as a device for optically scanning and measuring the environment of the laser scanner 10. The laser scanner 10 has a measuring head 12 and a base 14. The measuring head 12 is mounted on the base 14 as a unit that can be rotated about a vertical axis. The measuring head 12 has a rotary mirror 16, which can be rotated about a horizontal axis. The intersection point of the two axes of rotation is designated as the center C₁₀of the laser scanner 10.
The measuring head 12 is further provided with a light emitter 17 for emitting an emission light beam 18. The emission light beam 18 may be a laser beam in the range of approximately 300 to 1600 nm wave length, for example 790 nm, 905 nm or less than 400 nm; however, other electro-magnetic waves having, for example, a greater wave length can be used. The emission light beam 18 is amplitude-modulated, for example with a sinusoidal or with a rectangular-waveform modulation signal. The emission light beam 18 is emitted by the light emitter 17 onto the rotary mirror 16, where it is deflected and emitted to the environment. A reception light beam 20 which is reflected in the environment by an object O or scattered otherwise, is captured again by the rotary mirror 16, deflected and directed onto a light receiver 21. The direction of the emission light beam 18 and of the reception light beam 20 results from the angular positions of the rotary mirror 16 and the measuring head 12, which depend on the positions of their corresponding rotary drives which, in turn, are registered by one encoder each.
A control and evaluation unit 22 has a data connection to the light emitter 17 and to the light receiver 21 in the measuring head 12, whereby parts of the unit 22 can be arranged also outside the measuring head 12, for example a computer connected to the base 14. The control and evaluation unit 22 determines, for a multitude of measuring points X, the distance d between the laser scanner 10 and the illuminated point at object O, from the propagation time of the emission light beam 18 and the reception light beam 20. For this purpose, the phase shift between the two light beams 18 and 20 can, for example, be determined and evaluated.
Scanning takes place along a circle by means of the relatively quick rotation of the rotary mirror 16. By virtue of the relatively slow rotation of the measuring head 12 relative to the base 14, the entire space is scanned step by step, by way of circles. The entity of measuring points X of such a measurement is designated as a scan. For such a scan, the center C₁₀of the laser scanner 10 defines the origin of the local stationary reference system. The base 14 rests in this local stationary reference system.
In addition to the distance d to the center C₁₀of the laser scanner 10, each measuring point X comprises a brightness information value which is determined by the control and evaluation unit 22 as well. The brightness value is a gray-tone value which is determined, for example, by integration of the bandpass-filtered and amplified signal of the light receiver 21 over a measuring period which is attributed to the measuring point X. A color camera can optionally generate pictures, by means of which colors (R, G, B) can be assigned to the measuring points as values.
A display device 24 is connected to the control and evaluation unit 22. The display device 24 is integrated into the laser scanner 10, in the present case into the measuring head 12. The display device 24 shows a preview of the scan.
The laser scanner 10 has a carrying structure 30 which serves as a skeleton of the measuring head 12 and at which different components of the laser scanner 10 are fixed. In an exemplary embodiment, the metal carrying structure 30 is made of aluminum and in one piece. Above the base 14, the carrying structure 30 has a traverse 30 a which is visible from the outside and which, at both ends, carries two walls 30 b, which are parallel to one another and project upwards from the traverse 30 a. Two shells 32 are configured as a housing which is open to one side. The shells 32 may comprise a plastic material. Each of the two shells 32 covers part of the components of the laser scanner 10 which are fixed to the carrying structure 30 and is assigned to one of the two walls 30 b, to which it is fixed (e.g., sealed with a sealing material). The walls 30 b and the shells 32 thus serve as a housing of the laser scanner 10.
On the outer side of each of the two shells 32 a yoke 34, which may comprise a metal material, is arranged, which partially covers and thus protects the corresponding shell 32. Each yoke 34 is fixed to the carrying structure 30, and more precisely on the bottom of the traverse 30 a. In an exemplary embodiment, each yoke 34 is made of aluminum and is screwed to the traverse 30 a at the side of the base 14. Each yoke 34 extends from its fixing point at the bottom of the traverse 30 a obliquely to the next outer corner of the assigned shell 32, from where it extends along the outer edge of shell 32 to the outer corner of shell 32 which is above, on the upper side of shell 32 obliquely up to the wall 30 b, a short distance along it, and then mirror-symmetrically to the described course on the upper side of shell 32, obliquely to the other outer corner, along the outer edge of shell 32 to the outer corner of shell 32 which is below and obliquely to the other fastening point at the bottom side of traverse 30 a.
The two yokes 34 together circumscribe a convex space, within which the two shells 32 are completely arranged; i.e., the two yokes 34 together project over all outer edges and outer surfaces of the shells 32. On top and on the bottom the oblique sections of the yokes 34 project over the top and/or bottom of the shells 32, on the four other sides, two sections each extending along an outer edge of the shells 32. The shells 32 are thus protected extensively. Although each of the yokes 34 primarily has a protective function, particularly with respect to impacts which might damage the shells 32 and the components of the laser scanner 10 which are arranged below, further functions can be integrated in one or both of the yokes 34, for example a gripping possibility for carrying the laser scanner 10 and/or an illumination.
Further details of the design of the laser scanner 10 are described for example in German Patent Application No. DE 10 2009 055 988 B3, the relevant disclosure of which is expressly incorporated by reference herein.
In embodiments of the present invention, two different operating modes may be provided for the laser scanner 10.
In a sphere mode, the base 14 is arranged in the environment in a stationary manner, the mirror 16 rotates about its horizontal axis, and the measuring head 12 rotates about its vertical axis. The two rotations define a sphere, by which the laser scanner 10 scans its environment (e.g., completely).
In a helix mode, the base 14 moves relative to its environment along a line, the mirror 16 rotates about its horizontal axis, and the measuring head 12 rests relative to the base 14. The rotation and the movement along the line define a helix, by which the laser scanner 10 scans its environment (e.g., partially). On principle, the line can have any shape. However, the line may usually comprise straight and/or slightly curved sections.
For the helix mode, the laser scanner 10 is mounted on a cart W, for example on a motor vehicle. A mounting device 40 is provided for this purpose, which may be fixedly connected both mechanically and electrically with both the cart W and the laser scanner 10.
In the exemplary embodiment, the mounting device 40 has an approximately cylindrical body 40 a, the diameter of which is slightly bigger than that of the base 14. Two pairs of fixing pins 40 p (e.g., rotatable screws) protrude from the upper face of the body 40 a of the mounting device 40. The fixing pins 40 p interact with suitable fixing holes 14 p configured on the underside of the base 14. A pre-positioning by the fixing pins 40 p may likely be subject to backlash. This is why, from the upper face of the mounting device 40, two additional positioning pins 40 f protrude which interact with suitable positioning holes 14 f on the underside of the base 14. Each of the positioning pins 40 f is arranged between the two fixing pins 40 p of a pair. When the fixing pins 40 p enter the assigned fixing holes 14 p (i.e., are screwed in), the positioning pins 40 f enter the assigned positioning holes 14 f. The positioning pins 40 f are configured to be fixed relative to the basic body 40 a. At least one of the two positioning pins 40 f may have a conical end, which, when entering the assigned positioning hole 14 f, provides for an absence of backlash and a force closure. In addition to the mechanical fixing elements, electrical connecting elements are provided, in an exemplary embodiment on the upper face of the body 40 a, an integrated contact bushing 40 s with flat contacts and on the underside of the base 14, an integrated mating contact plug 14 s with spring pins.
On the circumferential surface of the body 40 a, the mounting device 40 has at least two screw-in holes 40 u (or alternatively other fixation means) for the mechanical connection with the cart W and at least one terminal for the electrical connection with the cart W. The electric connecting elements 14 s, 40 s and 40 v allow for transmission of both data and energy. The assignments of male and female electric connecting elements to the base 14 and to the mounting device 40 can also be exchanged. The same applies to the mechanical connecting elements 14 f, 14 p and 40 f, 40 p.
The mounting device 40 is connected mechanically to the laser scanner 10 by the above-described mechanical connecting elements 14 f, 14 p, 40 f and 40 p (i.e., a mechanical connecting mechanism) at the base 14 of the laser scanner 10. The mounting device 40 is also connected electrically to the laser scanner 10 by the electric connecting elements 14 s and 40 s (i.e., an electrical connecting mechanism). In the event of an agitated movement of the cart W during the helix mode, the measuring head 12 with its inertia may stress with changing moments its pivot bearing in the base 14. According to embodiments of the present invention, the mounting device 40 therefore is not only fixedly connected with the base 14, but it is also locked with the measuring head 12. For this purpose, the mounting device 40 interacts with the yokes 34, and consequently with the carrying structure 30.
Each of the two yokes 34 has, in the immediate vicinity of the fixation of the yoke 34 to the carrying structure 30 (i.e., in an embodiment the screw points at the traverse 30 a), a first locking mechanism 34 k. The two first locking mechanisms 34 k are thus fixed to the carrying structure 30. Each first locking mechanism 34 k is configured, in an embodiment, as a notch in the yoke 34 with flanks which taper in a wedge-shaped manner, wherein the yoke 34 opens radially outward with respect to the axis of rotation of the measuring head 12. The two first locking mechanisms 34 k thereby open in opposite directions. The two first locking mechanisms 34 k can also be formed on the carrying structure 30 (i.e., configured in one piece with the structure 30) or may be separate components which are fixed to the yokes 34 or to other parts of the carrying structure 30.
The mounting device 40 has, on its body 40 a and offset to each of the pairs of fixing pins 40 p and positioning pins 40 f, a pillow block 40 i. The pillow blocks 40 i are curved in an arc-shaped manner with an almost square cross section. The pillow blocks 40 i, which may be configured in one piece, have in their center a central area, as well as wing areas on the sides thereof. The wing areas serve for fixing the corresponding pillow block 40 i, relatively more precisely for receiving fixing screws. The wing areas may be omitted if the pillow block 40 i is fixed in another manner. The central area is elevated with respect to the wing areas, so that the wing areas of the pillow blocks 40 i are spaced from the yokes 34, if the base 14 bears on the upper face of the basic body 40 a. For a pre-positioning, however, the central area of each pillow block 40 i can be dimensioned in such a way that it engages between the assigned yokes 34.
Each pillow block 40 i pivotably mounts a second locking mechanism 40 k which, in an embodiment, may be configured as a pin-shaped lock with a support which bears it. The two second locking mechanisms 40 k can pivot from a radial initial position with respect to the body 40 a into an axial final position and back. A pre-bias of each of the two second locking mechanisms 40 k is provided in the initial position and in the final position, for example by a spring which has a dead point between an initial position and a final position. In a modified embodiment, a pre-bias is provided only for the final position. The two second locking mechanisms 40 k may be pivoted manually. Regarded from above, the positioning pins 40 f and the second locking mechanisms 40 k are arranged crosswise, i.e., the connection lines intersect, in an embodiment, at an angle of 90°. Alternative arrangements are possible, however. The at least one electrical connecting element 40 v for the electrical connection with the cart W may be located adjacent to the second locking mechanisms 40 k, in an embodiment below the central area of one of the pillow blocks 40 i and consequently outside the space angle which is reached by the emission light beam 18.
To connect the mounting device 40 with the laser scanner 10, the scanner 10 is placed with its base 14 on the body 40 a and is positioned by the positioning pins 40 f and the positioning holes 14 f, without backlash in the final position. At the same time, the contact plug 14 s is plugged into the contact bushing 40 s. The fixing pins 40 p then are moved, i.e., screwed into the fixing holes 14 p, the base 14 thus being connected without backlash with the mounting device 40. Finally the two second locking mechanisms 40 k are pivoted into their final position. Shortly before reaching the final position, they approach from the radial direction the corresponding one of the two first locking mechanisms 34 k which are configured as notches and finally engage therein, if necessary by sliding along the flanks of the notches (e.g., the flanks being tapered in a wedge-shaped manner), until the measuring head 12 is locked without backlash with the mounting device 40.
A completely strain-free locking may be achieved by the measuring head 12 being aligned as precisely as possible with respect to its angle position relative to the base 14 at the latest before the two second locking mechanisms 40 k are pivoted into their final position, so that, by both the two first locking mechanisms 34 k and the two second locking mechanisms 40 k, only the backlash of the rotary drive of the measuring head 12 needs to be eliminated or reduced. Since the angle position of the measuring head 12 is registered by an encoder, a calibration of the encoder may be advantageous. Alternatively, a smoothly running idle movement of the rotary drive or a relatively large backlash of the same can be provided, so that the two first and second locking mechanisms 34 k and 40 k themselves carry out the relatively precise alignment of the measuring head 12.

Claims

What is claimed is:

1. A laser scanner device for optically scanning and measuring an environment, the laser scanner comprising a base, a measuring head which is rotatable relative to the base, and a mirror which is rotatable relative to the measuring head, wherein, in at least one operating mode, the laser scanner is mounted on a cart by a mounting device, the cart moves the base which is fixedly connected with the mounting device, the measuring head rests relative to the base, and the mirror rotates, wherein in the at least one operating mode the measuring head is locked with the mounting device by at least one first locking mechanism, and wherein

mechanical and electric connecting mechanisms are provided which interact between the base and the mounting device to connect the base with the mounting device.

2. The device of claim 1, wherein the measuring head has a carrying structure, and wherein the at least one first locking mechanism is fixed to the carrying structure.

3. The device of claim 2, wherein as part of a housing of the laser scanner, at least one shell is provided on the measuring head, the outside of the shell being partly covered by at least one yoke serving as protection and being fixed to the carrying structure.

4. The device of claim 3, wherein the at least one first locking mechanism is configured on the yoke in the form of a notch which, with respect to an axis of rotation of the measuring head, points radially outwards.

5. The device of claim 1, wherein the mounting device supports at least one of a second locking mechanism.

6. The device of claim 5, wherein the mounting device has at least one pillow block, which pivotably supports the at least one of a second locking mechanism.

7. The device of claim 6, wherein the mounting device has a body on the face of which the base bears with its bottom side and on which the mechanical and electric connecting mechanisms are arranged.

8. The device of claim 7, wherein the pillow block is arranged on an upper face of the body.

9. The device of claim 1, wherein the measuring head includes a light emitter that emits an emission light beam which is deflected into the environment by the mirror, and a light receiver that receives a reception light beam which is reflected by an object in the environment or scattered otherwise, the device further comprising a a control and evaluation unit that determines, for a multitude of measuring points each, at least the distance to the object.